{smcl}
{* 15jun2006}{...}
{cmd:help mata mm_posof()}
{hline}

{title:Title}

{p 4 4 2}
{bf:mm_posof() -- Find element in vector}


{title:Syntax}

{p 8 12 2}
{it:real scalar}
{cmd:mm_posof(}{it:haystack}{cmd:,} {it:needle}{cmd:)}

{p 4 8 2}
where

              {it:haystack}:  {it:transmorphic vector haystack}
                {it:needle}:  {it:transmorphic scalar needle}


{title:Description}

{p 4 4 2} {cmd:mm_posof()} returns the position of the first
occurrence of element {it:needle} in
vector {it:haystack}, or 0 if {it:needle} does not occur.

{p 4 4 2}Note that {cmd:mm_posof()} is now outdated by the more
flexible and faster {bf:{help mf_mm_which:mm_which()}} function.
({cmd:mm_posof()} has been written before the appearance of the
{cmd:select()} function Mata.)


{title:Remarks}

{p 4 4 2}{cmd:mm_posof()} may be used with numeric elements or
with string elements. For example:

        {com}: mm_posof(("one","two","three"),("two"))
        {res}2
        {txt}
        {com}: mm_posof((1,2,3),(3))
        {res}3{txt}

{p 4 4 2}However:

        {com}: mm_posof((1,2,3),("2"))
        {res}0{txt}

{p 4 4 2}Furthermore:

        {com}: mm_posof(("one","two","three"),("four"))
        {res}0{txt}


{title:Conformability}

    {cmd:mm_posof(}{it:haystack}{cmd:,} {it:needle}{cmd:)}
    {it:haystack}: 1 {it:x c} or {it:r x} 1
      {it:needle}: 1 {it:x} 1
      {it:result}: 1 {it:x} 1.


{title:Diagnostics}

{p 4 4 2}{cmd:mm_posof()} returns 0 if the element types of
{it:needle} and {it:haystack} are different.


{title:Source code}

{p 4 4 2}
{help moremata_source##mm_posof:mm_posof.mata}


{title:Author}

{p 4 4 2} Ben Jann, University of Bern, jann@soz.unibe.ch


{title:Also see}

{p 4 13 2}
Online:  help for {bf:{help mf_mm_which:mm_which()}},
{bf:{help m4_utility:[M-4] utility}},
{bf:{help mf_strpos:[M-5] strpos()}},
{bf:{help moremata}}
